JP3728042B2 - Sheet conveying method, sheet conveying apparatus using the method, image reading apparatus, and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device having a configuration for conveying a sheet, such as a printing machine, a bookbinding machine, a copying machine, a printer, and a facsimile machine.
[0002]
[Prior art]
Conventionally, as a method for correcting the skew of a sheet being conveyed, the sheet is applied to an application roller called a registration roller because of its configuration and ease of control.
[0003]
However, in recent years, it has become necessary to increase the amount of sheets handled per unit time in order to increase the operation speed of these copying machines and the like. For this reason, the distance between continuously fed sheets tends to be narrow, and the sheet conveying speed tends to increase. In such a situation, in the method of transporting after once contacting the registration roller, the sheet transported from the rear collides with the previous sheet, so that there is a limit to speeding up the sheet transport. Therefore, a method of correcting the conveyance direction based on the skew amount detected by the skew amount detection means without applying the sheet to the registration roller, for example, adjusting the speeds of two independent rollers while being conveyed. A dynamic skew correction method for correcting skew has been proposed.
[0004]
[Problems to be solved by the invention]
However, such a dynamic skew correction method does not have a standard for positioning the sheet as compared with the conventional skew correction method using registration rollers, and the skew correction is performed by controlling the conveyance roller. However, how to transmit to the sheet is the biggest problem when performing accurate skew correction.
[0005]
In particular, the conveying means such as the conveying roller conveys the sheet conveying force from the surface of the sheet, so the conveying force transmitted to the sheet varies depending on the thickness and surface roughness of the sheet. Of course, the sheet size, material (mass), etc. However, since the amount of skew correction is different, the correction effect by the dynamic skew correction means varies.
[0006]
Furthermore, due to arrangement restrictions, the correction effect by the dynamic skew correction means could not be dealt with even when the contact portion with the sheet became smaller or the conveyance means deteriorated. .
[0007]
The present invention has been made to solve the above-described problems of the prior art, and the object of the present invention is to eliminate variations in skew correction due to sheet characteristics and other conditions, and to stably provide a sheet in any case. An object of the present invention is to provide a sheet conveying method with high accuracy and a sheet conveying apparatus using the method.
[0008]
[Means for Solving the Problems]
  To achieve the above object, the present invention1st inventionIs
  A skew amount detecting means for detecting the skew amount of the sheet being conveyed;
  SaidAccording to the detection value obtained by the skew amount detection unit, the conveyance unit is controlled to correct the sheet conveyance direction.DoIn the sheet conveying method,
  A post-correction skew amount detection means for detecting the skew amount after correction in the sheet conveyance direction;
  SaidObtained by the skew amount detection meansThe control amount of the conveying means corresponding to the detected value isJudging from the characteristics of the sheetTransport conditionsOn the basis of theadjustIn addition, the control amount of the transport unit is fed back and adjusted from the detection value obtained by the corrected skew amount detection unit.It is characterized by that.
  The second invention of the present invention is:
  A skew amount detecting means for detecting the skew amount of the sheet being conveyed;
  In the sheet conveying method for correcting the sheet conveying direction by controlling the conveying unit according to the detection value obtained by the skew amount detecting unit,
  The control amount of the conveying unit corresponding to the detection value obtained by the skew amount detecting unit is adjusted based on the conveying condition determined from the characteristics of the sheet, and the sheet on which a predetermined image is recorded is conveyed. After being conveyed by the method, the image is read by the reading unit, the distortion of the read image is detected, and the control amount of the conveying unit is fed back and adjusted.
[0009]
  Thus, it is possible to control not only the skew amount but also the conveying means corresponding to the sheet conveying conditions, and accurate skew correction can be performed under any sheet conveying conditions.In addition, even when accurate skew correction cannot be performed due to factors other than those that can be detected in advance, the deviation between the skew amount and the control amount caused by the conveyance conditions can be eliminated by learning.
[0010]
  The control of the conveying means independently drives a pair of conveying rollers arranged on a line orthogonal to the sheet conveying direction.TwoBy controlling the driving speed of the driving sourceDoIt is characterized by that.
[0011]
Thereby, it is possible to accurately control the conveying means with a simple configuration.
[0012]
It has sheet characteristic detecting means for detecting the characteristic of the sheet, and the condition for conveying the sheet is judged based on the detection value obtained by the detecting means.
[0013]
As a result, it is possible to control the conveying unit corresponding to all types of sheets having different characteristics, and to perform an optimum sheet skew correction.
[0014]
The sheet characteristic detecting means includes sheet size detecting means for detecting the size of the conveyed sheet.
[0015]
As a result, the conveying means can be controlled in correspondence with sheets of all sizes.
[0016]
The sheet characteristic detecting means includes sheet thickness detecting means for detecting the thickness of the conveyed sheet.
[0017]
  As a result,EtThe conveying means can be controlled in correspondence with a sheet having a moderate thickness.
[0018]
The sheet characteristic detecting means includes sheet surface roughness detecting means for detecting the surface roughness of the conveyed sheet.
[0019]
As a result, the conveying means can be controlled in correspondence with sheets having any surface roughness.
[0023]
A sheet conveying apparatus, comprising: a control amount adjusting unit that adjusts a control amount of the conveying unit from a detection value obtained by the skew feeding amount detecting unit and a sheet conveying condition; It is characterized by conveying.
[0024]
Further, the control amount adjusting means is capable of selectively adjusting the control amount selectively by an input from an operation unit.
[0025]
As a result, it is possible to cope with a deviation in control amount that cannot be automatically adjusted.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.
[0027]
(Embodiment 1)
1 to 11 show a first embodiment of the present invention.
[0028]
FIG. 1 is a schematic cross-sectional configuration diagram of a flow reading scanner which is an image reading apparatus provided with a sheet conveying apparatus according to a first embodiment of the present invention.
[0029]
Hereinafter, a case where the sheet conveying apparatus according to the present embodiment is applied to the document feeding apparatus will be described.
[0030]
In FIG. 1, 1 is a document feeding device as a sheet conveying device, 2 is a scanner main body, 103 is a document stacking tray, 104 is a document stacking tray lifter drive motor, 105 is a feeding roller, 106 is a separation roller, and 107 is a pulling-out device. Rollers 108, 109, 110, 111, and 112 are vertical path conveying rollers, 113 is a front surface reading and extracting roller, 118 is a back surface reading and extracting roller, 114 and 115 are double-sided paper discharging path conveying rollers, and 116 and 117 are reverse path conveying rollers. 119 is a paper discharge roller, 132 is a discharged document stacking tray, 120 is a skew feeding correction roller at the time of front reading, 121 is a skew feeding correction roller at the time of reading back, 127 is a document illumination lamp, 128 is a lens, 129 is an image reading CCD linear image sensor, 133 between skew correction rollers 120 and 121 Position is document reading table is an image reading position.
[0031]
With such a configuration, the sheet placed on the document stacking tray 103 is separated and fed by the paper feed roller 105, conveyed by various rollers, reaches the document reading table 133, and after the image is read, In the single-sided reading mode, the sheet is pulled out as it is by the pulling roller 113 and is stacked on the discharged document stacking tray by the discharge roller 119. At this time, in the double-sided reading mode, after being pulled out by the pulling roller 117 at one end, it reaches the original reading table 133 with the reverse path conveying rollers 116 and 113 facing down, and the back side image is read. Then, the paper is drawn out by the drawing roller 118 and discharged by the double-sided paper discharge path conveying rollers 114 and 115 and the paper discharge roller 119.
[0032]
2 and 3 are schematic configuration diagrams in which only the sink reading unit in FIG. 1 is enlarged, FIG. 2 is a front view, and FIG. 3 is a plan view.
[0033]
In FIG. 2, the position of the document reading table 133 between the skew feeding correction rollers 120 and 121 is the flow reading image reading position. 403LD and 404LD are light emitting elements, and light emitted from these elements is received by the light receiving elements of 403PD and 404PD, respectively, and functions as a sensor.
[0034]
403LD, PD, and 120 perform skew feeding correction and flow scanning when reading the document surface. Similarly, 404LD, PD, and 121 perform skew feeding correction and flow reading at the time of reading the back surface.
[0035]
Here, the front and back skew correction rollers 120 and 121 are arranged one by one in front as shown in FIG. 3, and on the front side, the skew correction roller 120 (skew correction roller 120- L and 120-R), skew correction is performed by changing the rotation speed of the motor 401 (401-L and 401-R, respectively), and the amount of skew is detected by the sensors 403PD and LD (each of which are detection means). 403PD-L, 403PD-R, 403LD-L, and 403LD-R).
[0036]
Similarly, on the back side, the skew correction is performed by changing the rotation speed of the motor 402 (402-L and 402-R, respectively) that is the drive source of the skew correction roller 121 (skew correction rollers 121-L and 121-R). The skew amount is detected by the detection time difference between the sensors 404PD and LD (404PD-L, 404PD-R, 404LD-L, and 404LD-R, respectively), which are detection means.
[0037]
Here, two sensors 403 and 404 are arranged on the upstream side and the downstream side in the transport direction as detection means for detecting the document transported by the skew correction rollers 120 and 121, but the present invention is not limited to this. Instead, for example, a configuration may be adopted in which document detection is performed using a CCD or the like instead of the sensor. Further, although a pulse motor which is a driving means for rotationally driving the skew feeding correction rollers 120 and 121 is illustrated, the present invention is not limited to this.
[0038]
In FIG. 2, reference numeral 204 denotes a thickness detection sensor which is a sheet thickness detection unit, 205 denotes a document surface detection sensor which is a sheet surface roughness detection unit, and 206 denotes a document width detection sensor which is a part of the sheet size detection unit. Is a trailing edge detection sensor during document conveyance.
[0039]
Hereinafter, the shape and function of each of these sensors will be described with reference to FIGS.
[0040]
First, sheet size detection means for detecting the size of the document will be described.
[0041]
The size of the document is detected by the sensors shown in FIGS. FIG. 4 shows a portion 231 in FIG. 2, and a document conveyance trailing edge detection sensor 231 serving as a sheet size detection unit includes an encoder 301 and a photo interrupter 302. The encoder is in contact with the original, and rotates according to the movement of the original while the original is being fed by the paper feed roller.
[0042]
The output as shown in FIG. t1 is an output of the photo interrupter 302 before the document starts moving.
[0043]
During document feeding, toggle output is performed as in the section t2, and when the trailing edge of the document exits the encoder 301, the output does not change as in t3.
[0044]
The size in the document transport direction is detected by counting the time t2 or the number of pulses.
[0045]
FIG. 5 is an explanatory diagram of the size detection means 206 in the cross track direction (direction perpendicular to the transport direction) of the document.
[0046]
In FIG. 5, reference numeral 303 denotes a side guide for regulating the document in the cross track direction.
[0047]
This side guide 303 is moved according to the paper when different types of paper such as A-series and B-series are placed (automatic or manual).
[0048]
The gear 304 is moved in conjunction with the movement of the side guide 303.
[0049]
The gear 304 is connected to a potentiometer 305. The position of the side guide is known from the position of the potentiometer, and the size in the cross track direction is detected. Further, by combining with the size detection result in the transport direction, it is detected whether the document is laterally fed or vertically fed.
[0050]
The potentiometer 305 may be configured in the same unit as the gear 304.
[0051]
Alternatively, the same configuration can be made by using a volume resistor or an encoder.
[0052]
Next, the sheet thickness detecting means 204 for detecting the thickness of the document will be described with reference to FIG.
[0053]
As a sheet thickness detecting means generally used,
1. The thickness measured by the principle of triangulation at the edge of the fed document is detected (FIG. 6A).
2. Light is applied to the document being conveyed, and the thickness of the document is determined from the amount of transmitted light (FIG. 6B).
3. The thickness of the original is detected from the amount of displacement with or without the original, which is in contact with the original such as a conveyance roller (FIG. 6C)
There is something like this.
[0054]
In FIG. 6A, light emitted from a light emitting element 903 (infrared LED) as a light source passes through a light projecting lens 905 designed to obtain sufficiently sharp directional LED light, and is measured. When the reflected light from the object is condensed on the light receiving element by the light receiving lens 906, the position of the light receiving spot on the light receiving element 904 changes according to the distance of the object to be measured. By detecting this light receiving spot position electronically, the distance to the object to be measured can be obtained.
[0055]
  As shown in the figure, the distance (base line length) between the center of the light projecting lens 905 and the light receiving lens 906 is A, the focal length of the light receiving lens 906 is f, and the expanse of the LED light flux and the thickness and aberration of the lens are not considered for convenience. WhenShiAssume that the light receiving surface is located at a position where the distance from the light receiving lens 906 is f.
[0056]
When the distance l1 to the object to be measured is geometrically determined from the position x1 of the light receiving spot,
l1 = A · f / x1
It becomes. When the distance to the object to be measured becomes 12, the light receiving spot position becomes x2, and similarly, l2
l2 = A · f / x2
It is calculated by.
[0057]
In order to electrically detect the light receiving spot position by the triangulation method, a light receiving element such as a PSD (Position Sensitive Detector) or a multi-division photodiode is used. A PSD capable of obtaining output characteristics with high accuracy (high resolution) is employed. Furthermore, in order to obtain a sharp directional LED beam necessary for obtaining an accurate distance measurement result, a current confining type LED is used, and an aspheric lens is used to reduce spherical aberration, coma aberration, etc. I am designing a lens.
[0058]
Reference numeral 902 denotes a document feeder lift-up unit, and reference numeral 901 denotes a document tray. The document tray 901 moves up and down to move the documents stacked on the tray to an appropriate paper feed position.
[0059]
Reference numeral 907 is a thick representation of one original.
[0060]
Using the principle described above, the thickness of the document is determined from the change in distance from l2 to l1 when 907 is fed.
[0061]
During this determination, the original tray 901 is not moved up and down, but the distance is measured at a fixed position.
[0062]
Next, FIG. 6B and FIG. 6C will be described.
[0063]
In FIG. 6B, the light emitted from the light emitting side passes through the paper and enters the light receiving element. Ordinary paper normally used in copying machines and printers can transmit light from the light emitting section. Since the amount of transmitted light naturally varies depending on the thickness of the paper, the thickness of the paper is determined based on the voltage value using the transmitted light as a photoelectric change.
[0064]
FIG. 6C shows a method of determining the thickness of the document from the gap between the pair of rollers that convey the document. The upper roller in FIG. 6C swings up and down according to the thickness of the document. This movement is measured with a displacement meter to determine the thickness of the document. The displacement meter can be composed of the PSD used in FIG. Further, it can be constituted by a strain measuring device using a piezoelectric element or a pressure element.
[0065]
In the present embodiment, 3 is adopted because it is not easily affected by the document density and has relatively high accuracy. However, the sheet thickness detecting means in the present invention is not limited to this, and the above 1 Alternatively, the method 2 may be used, and furthermore, a sheet thickness detecting unit not listed here may be used.
[0066]
Next, sheet surface roughness detection means for detecting the surface roughness of the document will be described with reference to FIG.
[0067]
The document surface detection sensor 205 (FIG. 2), which is a sheet surface roughness detection means,
1. Surface glossiness is detected from the amount of reflected light (FIGS. 7A and 7B).
2. The surface property is detected by taking the difference between the longitudinal wave light and the transverse wave light (FIG. 7C), or the surface property is detected from the difference between the two light beams that are 180 degrees out of phase.
Such a method can be applied.
That is, in FIG. 7A, reference numeral 811 denotes a reflection type photosensor as a document surface detection sensor. A light emitting unit 812 and a light receiving unit 813 are built in the reflection type photosensor, and the internal connection is as shown in FIG. The light emitting unit 812 is an LED, and the light receiving unit 813 is a phototransistor. The phototransistor of the light receiving portion 813 is a photoelectric conversion element, and tries to flow a current from the C terminal to the E terminal in FIG. 7B according to the amount of light.
[0068]
The light emitted from the light emitting unit 812 strikes the original 814, and the reflected light enters the light receiving unit 813. At this time, if the document surface is glossy, the amount of light entering the light receiving unit 813 is large, and if the document has a rough surface, the amount of light entering the light receiving unit 813 is small. Since the difference in the amount of light is proportional to the amount of current flowing from the C terminal in FIG. 7B, an interface as shown at 815 is provided to convert the current flowing into the C terminal into a voltage and monitor it.
[0069]
FIG. 7C is a diagram in which a composite wave of a longitudinal wave and a transverse wave is irradiated from obliquely above the paper, and the surface roughness of the paper is known by observing the transparency and reflectivity of the two types of waves. Shows how.
[0070]
In the present embodiment, since the image is printed on the document, the second method is adopted. However, the present invention is not limited to this method, and the sheet conveying device according to the present invention is formed in particular. When the surface roughness is detected with respect to the transfer paper, such as when applied to a portion, it is considered to be a blank paper state, so it is preferable to use the first method.
[0071]
As described above, when the characteristics of the original document that is a sheet is detected during conveyance by various sensors and the conveyance conditions are determined, the result of the determination is the control amount of the motor 141 (or 142) described in FIG. It is reflected in.
[0072]
In particular, a description will be given only when reading the image on the front side. As shown in FIG. 8, when the document S that has been transported obliquely passes through the sensors 403-L and 403-R, the time difference between them. The control amount of the motor 401 is determined with respect to the time difference. At that time, adjustments are made according to the conveyance conditions determined from the characteristics of the original detected by the sensor.
[0073]
Then, according to the control amount, as shown in FIG. 8B, for example, the rotational speed of 401-R or 401-L is slowed (or increased), or the rotational speed of 401-R is slowed down. The skew correction is performed by increasing the rotational speed of 401-L (FIG. 8C).
[0074]
Further, in order to confirm the straightness of the paper subjected to the skew correction, the time difference at the trailing edge of the paper is measured by 403LD, PD and 404LD, PD. That is, skew amount measurement for skew correction is measured at the leading edge of the conveyed paper, and after skew correction is performed, the skew amount after correction is measured at the trailing edge of the paper. By this method, the degree of correction is confirmed for each sheet subjected to skew correction control, and the motor control amount derived from the transport conditions is readjusted.
[0075]
In FIG. 8, 411-R and L are encoders for detecting the rotational speed of each motor. These are for monitoring whether the motor is rotating at a predetermined speed. These are also attached to the skew correction roller on the back side (412-R, L in FIG. 3). If the motor is not rotating at a rotational speed corresponding to the clock sent from the CPU, the machine is stopped as an error.
[0076]
Next, in the skew correction, how to adjust the control amount of the motor according to the conveyance condition will be described in detail.
[0077]
First, the skew correction pulse rate (here, the difference between the rotation speeds of the two motors in terms of the pulse amount) is calculated from the skew amount, the feed amount per pulse, the conveyance speed, and the correction time. The
[0078]
For example, in a two-phase excitation drive of a two-phase hybrid stepping motor, one step is 1.8 degrees. If a roller having a diameter of 20 mm is driven by this motor, the feed amount per step is 0.314 mm. Now, assuming that the amount of skew read by the sensor is 6.28 mm and the motor 401-R side is moving forward by that length, this corresponds to 20 pulses. In this way, the pulse conversion value of the skew amount (the skew amount indicated by the pulse amount input to the motor) is n.
[0079]
If the conveyance speed V that is uniquely set in the conveyance apparatus is 314 mm / s, the number of rotations on the motor shaft corresponds to 5 rps, and 1000 pps for the pulse rate f. That is, if the sent paper is to be conveyed at the same speed, a pulse voltage of 1000 pps may be input to the motor.
[0080]
The correction time t is the time from the start of correction to the end, and is a numerical value that is physically determined by the configuration of the transport path. For example, if it is desired to end the correction within a distance of 31.4 mm from the positional relationship with the transfer roller, the correction time is 0.1 s because the conveyance speed is 314 mm / s.
[0081]
In other words, in order to correct the skew of 6.28 mm within 0.1 s, the motor 401-L is driven at 1000 pps, and only the motor 401-R is driven at 800 pps for the correction time of 0.1 s. It ’s fine.
[0082]
The skew correction motor clock frequency fr (in this example, the motor clock frequency of the motor 401-R) is simplified.
fr = f− (n / t).
[0083]
Here, a correction coefficient a is selected based on the thickness data detected by the document thickness sensor and the surface data from the surface detection sensor in order to adjust the control amount according to the characteristics of the document.
fr = a {f− (n / t)}
The driving frequency is determined as follows.
[0084]
This coefficient is a numerical value obtained in advance by experiment, and is stored in the memory as a table as shown in FIG.
[0085]
In this example, only the motor clock frequency of the motor 401-R is controlled. However, the motor 401-L may be controlled to 1200 pps and the motor 401-R may be controlled to 1000 pps, or the motor 401-L may be controlled to 1100 pps and the motor 401-R may be controlled. It may be driven at 900 pps.
[0086]
  FIG.,It is a block diagram showing the electric constitution of this Embodiment. Here, reference numeral 451 denotes a central processing unit (CPU) that performs control. Reference numerals 406 and 407 denote memories in which programs and data are stored. Each sensor of 403PD-L, 403PD-R, 404PD-L, 404PD-R, 231, 205, 204, 411-L, 411-R, 412-L, 412-R is connected to the CPU input port. , 403LD-L, 403-LD-R, 404LD-L, 404LD-R, and motor drivers 405a, b, c, and d are connected to an output port of the CPU. CPU 451eachThe coefficients in FIG. 9 are selected based on the detection signal from the sensor, and a clock is generated from the output port for the motor drivers 405a, b, c, d, and the motors 401-L, 401-R, 402-L, 402 are generated. -R is driven.
[0087]
In FIG. 11, the control flow of the CPU 451 will be described using a flowchart.
[0088]
When a copy start is instructed in S1, first, in S2, the document length in the cross track direction is detected from the value 206 in FIG. 2 described above.
[0089]
Here, if this length is detected as 297 mm, for example, it can be limited to either A4 vertical feeding or A3 horizontal feeding for a standard size paper.
[0090]
Similarly, if the cross track size is known for other standard size papers, the paper size can be determined by determining whether the feed is vertical or horizontal.
[0091]
  Thereafter, document feeding is started at S3, and the in-track length is determined at 231 in FIG. Next, in 205, the surface property of the document is detected for both the front and back sides (S5), and in 204, the thickness is detected (S6). Based on the detection results of these sheet characteristics, coefficients are selected from the table of FIG.(S7).
[0092]
The amount of skew of the original is detected immediately before the reading unit (S8), the above-described drive frequency fr is calculated from the amount of skew (S9), and the selected coefficient is multiplied (S10).
[0093]
Skew correction control is performed with the value (S11), and after the control, the degree of skew correction is confirmed at the trailing edge of the paper (S12). If the skew amount is 0 in S12, the correction has been successfully performed. However, if skew is still detected there, there is an excess or deficiency of control, and the table in FIG. 9 is rewritten in S13.
[0094]
Here, S4, S5, and S6 are out of order, and the same result can be obtained even if the order is changed.
[0095]
Further, although the table is rewritten in S13, a method of adjusting sensors such as 205 and 204 can also be implemented with this configuration.
[0096]
With the configuration and control as described above, the characteristics of the document can be detected by various sensors, skew feeding can be corrected according to the characteristics, and other conveyance conditions can be obtained by applying feedback from the correction results. In consideration, skew can be corrected. That is, it is possible to perform a very accurate skew correction in accordance with every conveyance condition.
[0097]
(Embodiment 2)
FIG. 12 shows a control method according to the second embodiment of the present invention. This block diagram is configured by hardware without using a CPU for control.
[0098]
1001, 1002 are frequency-voltage converters, 1006, 1007, 1012 are analog-digital converters, 1005 is a differentiator, and 1006 is a counter and shift register circuit.
[0099]
The outputs of the rear end detection sensor 131 are input to the F / V converters 1001 and 1002 and converted into analog voltages. The analog output converted by the F / V converter is converted into a digital value by A / D converters 1003 and 1004.
[0100]
A / D converters 1006, 1007, and 1012 receive signals from surface detection sensors 205U and L and thickness detection sensor 204, respectively, and are input to decoder 1009 as digital values.
[0101]
A motor clock pattern generator, a multiplier, and a correction coefficient are built in the decoder 1009 (not shown).
[0102]
A control method in such a configuration will be described with reference to FIG.
[0103]
When conveyance is started, a pulse-like output is output from 231. The length in the in-track direction of the paper is during this pulse (the cross track length is assumed to be detected in advance as a steady one). An output is output from the converter 1001. This output section is used as an enable signal for the counter 1003 by the comparator 1002. Thus, the counter 1003 counts the pulse interval from 231, and the comparator 1008 compares it with the set value to determine whether or not the document is fed in the horizontal / vertical direction. (The same effect can be obtained by using the counter value as it is.)
The values 205 (front and back) and 204 are encoded by the A / D converters 1006, 1007, and 1012 into digital signals of 2 bits per corner.
[0104]
The decoder of 1009 sets a value of 1010 by a combination of 1008 output, 1006 output, 1007 output, and 1012 output. A counter & shift register 1010 generates a clock to the motor according to a set value.
[0105]
Then, a calculation is performed by multiplying the clock to the motor by a correction coefficient in accordance with the output from the decoder, and the motor drive frequency at the time of skew correction is adjusted.
[0106]
As described above, accurate skew correction can be performed without using the CPU as in the first embodiment.
[0107]
(Other embodiments)
In the above-described embodiment, the document feeding device provided with the reading mechanism for reading the image of the conveyed document is exemplified as the sheet conveying device to which the present invention is applied. However, the present invention is not limited to this, and for example, copying In the image forming apparatus such as an image forming apparatus or a facsimile machine, the above effect can be obtained even if the present invention is applied to a sheet conveying unit that sends a document as a sheet to the image reading unit or a sheet conveying unit that sends a recording medium as a sheet to the image forming unit. The same effect can be obtained.
[0108]
As an example of such an image forming apparatus, FIG. 14 shows a copying machine provided with a sheet conveying apparatus to which the present invention is applied.
[0109]
FIG. 14 is a schematic cross-sectional configuration diagram. 1 is a document feeding unit which is a sheet conveying device, 2 is an image reading unit which is also a scanner body, 3 is an operation unit, 4 is a printer unit, 5 is a paper feed deck unit, 6 Is the finisher section.
[0110]
The operation of the copying machine will be briefly described. Based on an input signal from the operation unit 3, the image reading unit 2 reads an image of the document fed by the document feeding unit 1 and converts it into an electrical signal. At the same time, the transfer material is fed from the paper feed deck unit 5 to the printer unit 4, and the printer unit converts the received electrical signal into image information and transfers it to the transfer material.
[0111]
Further, the values in the table of FIG. 9 can be changed by the operator inputting from the operation unit 3 shown in FIG.
[0112]
Further, in such a configuration, a specific pattern (not shown) is output from a printer (not shown), and this pattern is read by a scanner which is an image reading unit, whereby the number of lines on the paper is increased. It is also possible to detect whether it is tilted.
[0113]
In this way, an adjustment coefficient can be applied to the rotational speed control of the independent motor on the printer side based on the inclination of the line detected by the scanner.
[0114]
In this way, more accurate skew correction can be performed.
[0115]
【The invention's effect】
The present invention eliminates variations due to paper quality and paper size for correction of sheet skew during conveyance, and enables sheet conveyance with high accuracy in straight line conveyance under any conditions.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional configuration diagram of a continuous scanning scanner, which is an image reading apparatus, provided with a sheet conveying apparatus according to a first embodiment of the present invention.
FIG. 2 is an enlarged view showing a sensor arrangement of the sheet conveying apparatus according to the first embodiment of the present invention.
FIG. 3 is a schematic configuration plan view in which only the sink reading unit of FIG. 1 is enlarged.
FIG. 4 is a diagram illustrating an in-track direction size detection (document trailing edge detection) method and a sensor output signal used by the sheet conveying apparatus according to the first exemplary embodiment of the present invention.
FIG. 5 is an explanatory diagram of a method for detecting a cross-track direction size in the sheet conveying apparatus according to the first embodiment of the invention.
FIG. 6 is a principle diagram of a paper thickness detection method in the sheet conveying apparatus according to the first embodiment of the invention.
FIG. 7 is a principle diagram of a surface roughness detection method in the sheet conveying apparatus according to the first embodiment of the present invention.
FIG. 8 is a simplified explanatory diagram of skew correction in the sheet conveying apparatus according to the first embodiment of the present invention.
FIG. 9 is a control amount adjustment coefficient table for skew correction in the sheet conveying apparatus according to the first embodiment of the present invention.
FIG. 10 is a control block diagram of the sheet conveying apparatus according to the first embodiment of the present invention.
FIG. 11 is a control flowchart in the sheet conveying apparatus according to the first exemplary embodiment of the present invention.
FIG. 12 is a configuration diagram of an electric circuit in a sheet conveying apparatus according to a second embodiment of the present invention.
FIG. 13 is a timing chart of an output voltage in the sheet conveying apparatus according to the second embodiment of the present invention.
FIG. 14 is a schematic cross-sectional configuration diagram of a copying machine including a sheet conveying device to which the present invention is applied.
[Explanation of symbols]
1 Document feeder (document feeder)
2 Scanner body (image reading unit)
3 Operation part
4 Printer section
5 Paper feed deck
6 Finisher
103 Document stacking tray
104 Lifter drive motor for document stacking tray
105 Feeding roller
106 Separation roller
107 Drawing roller
108, 109, 110, 111, 112 Vertical path transport rollers
113 Surface reading drawing roller
114, 115 Double-sided paper discharge path transport roller
116, 117 Reverse path conveying roller
118 Back side reading drawing roller
119 Paper discharge roller
120-L, 120-R Skew correction roller for table reading
121-L, 120-R Skew correction roller for back side scanning
127 Document illumination lamp
128 lenses
129 CCD linear image sensor for image reading
132 Ejected document stacking tray
133 Document reader
401-L, 401-R Motor
403LD, 404LD Light emitting element (sensor)
403PD, 404PD Light receiving element (sensor)
204 Thickness detection sensor
205 Document surface detection sensor
206 Document width detection sensor
231 Rear edge detection sensor during document conveyance
301 Encoder
302 Photointerrupter
303 Side guide
304 Gear
305 Potentiometer
811 Reflection type photo sensor
812 Light emitter
813 Light receiver
901 Document tray
902 Document feeding unit lift-up unit
903 Light emitting device
904 Light receiving element
905 Floodlight lens
906 Light receiving lens

Claims (12)

A skew amount detecting means for detecting the skew amount of the sheet being conveyed;
In accordance with the detection value obtained by the skew amount detection means, by controlling the conveying means, the sheet conveying method for correcting the sheet conveying direction,
A post-correction skew amount detection means for detecting the skew amount after correction in the sheet conveyance direction;
The control amount of the conveyance unit corresponding to the detection value obtained by the skew amount detection unit is adjusted based on the conveyance condition determined from the sheet characteristics, and is obtained by the corrected skew amount detection unit. A sheet conveying method comprising adjusting a control amount of the conveying unit by feeding back the detected value . A correction coefficient based on the sheet conveyance condition is stored in a memory as a table, a control amount of the conveyance unit is adjusted by the correction coefficient, and a detection value of the post-correction skew amount detection unit is fed back to the memory. sheet conveying method according to claim 1 Symbol mounting, characterized in that rewriting the correction coefficient stored allowed table. A skew amount detecting means for detecting the skew amount of the sheet being conveyed;
In accordance with the detection value obtained by the skew amount detection means, by controlling the conveying means, the sheet conveying method for correcting the sheet conveying direction,
The control amount of the conveying unit corresponding to the detection value obtained by the skew amount detecting unit is adjusted based on the conveying condition determined from the characteristics of the sheet, and the sheet on which a predetermined image is recorded is conveyed. A sheet conveying method, comprising: conveying an image by the method; reading an image by a reading unit; detecting distortion of the read image; and feeding back and adjusting a control amount of the conveying unit . The control of the conveying means, claim to drive the transport roller pair arranged on a line perpendicular to the sheet conveyance direction independently, and performing Ri by the controlling the drive speed of the two drive sources 1 The sheet conveying method according to any one of claims 1 to 3 . Having sheet characteristic detecting means for detecting the characteristic of the sheet;
Wherein the resulting detected value by the detecting means, the sheet conveying method according to any one of claims 1 to 4, characterized in that to determine the transport conditions of the sheet. The sheet characteristic detection means, the sheet conveying method according to claim 5 Symbol mounting, characterized in that it comprises a sheet size detecting means for detecting the size of the sheet to be conveyed. The sheet characteristic detection means, the sheet conveying method according to claim 5 or 6 Symbol mounting characterized in that it comprises a sheet thickness detection means for detecting the thickness of the sheet to be conveyed. The sheet characteristic detecting means, any one Kouki placing a sheet conveying method according to claim 5 to 7, characterized in that it comprises a sheet surface roughness detection means for detecting the surface roughness of the sheet to be conveyed. And a conveyance condition of the detection value and the sheet over preparative obtained by the skew amount detection means, a control amount adjusting means for adjusting the control amount of the transport means, mounting any one Kouki of claims 1 to 8 A sheet conveying apparatus characterized by conveying a sheet by the sheet conveying method. Wherein said control amount adjusting means, the sheet conveying apparatus according to claim 9 Symbol mounting, characterized in that the input from the operation unit can adjust the controlled variable selectively manually. Image reading apparatus characterized by comprising a reading means for reading a document image of the sheet conveyed by the claims 9 or 10 SL placement of the sheet conveying device. On the sheet conveyed by the claims 9 or 10 SL placement of the sheet conveying apparatus, an image forming apparatus comprising the image forming means for forming an image.

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